Add PEM and DER acronyms (#95)

Author: alexandre-daubois

entities/acronyms.xml

@@ -66,6 +66,12 @@
     <simpara>Concurrent Versions System</simpara>
    </listitem>
   </varlistentry>
+  <varlistentry>
+   <term>DER</term>
+   <listitem>
+    <simpara>Distinguished Encoding Rules</simpara>
+   </listitem>
+  </varlistentry>
   <varlistentry>
    <term>DLL</term>
    <listitem>
@@ -240,6 +246,12 @@
     <simpara>PHP Extension and Application Repository</simpara>
    </listitem>
   </varlistentry>
+  <varlistentry>
+   <term>PEM</term>
+   <listitem>
+    <simpara>Privacy-Enhanced Mail</simpara>
+   </listitem>
+  </varlistentry>
   <varlistentry>
    <term>PHP</term>
    <listitem>